A polyethylene resin has mechanical and thermal properties affected by a molecular weight and a density thereof, which causes the application of the polyethylene resin to be varied. In general, the lower the density of the polyethylene resin, the better the transparency and low-temperature impact resistance, but the worse the physical properties, such as heat resistance, hardness and flexural modulus, and the higher an extract content.
Whereas, the higher the density of the polyethylene resin, the better the physical properties, such as heat resistance, hardness and flexural modulus and the lower the extract content, but the worse the transparency and low-temperature impact resistance. For this reason, when an injection product using an ethylene copolymer, particularly a refrigerating container, a food container, or the like, is manufactured, an injection product having high hygienic property and excellent low-temperature impact rigidity is remarkably difficult to manufacture. In particular, since the injection product such as a refrigerating container, a food container, or the like is highly required to have high hygienic property and excellent low-temperature impact rigidity, the necessity for these techniques is expected to be more increased.